MAZAR-E SHARIF, Afghanistan (Reuters) -- Taliban insurgents attacked a vehicle carrying boxes of ballot papers, killing one election official and setting fire to the boxes in northern Afghanistan, an official has said.

Millions of Afghans went to the polls on August 20, defying Taliban threats and sporadic attacks to choose a president amid worsening violence in only the second direct vote since the hard-line Islamists were overthrown in late 2001.

The Afghan government said nine civilians and 14 members of the security forces were killed in a total of 135 incidents countrywide on polling day.

The insurgents attacked the vehicle carrying counted ballot papers in northern Balkh Province on the night of August 20, Afghan National Army commander General Murad Ali told Reuters.

"An IEC [Independent Election Commission] official was killed and all the ballot papers were burnt," Ali said.

Taliban militants failed to mount a single spectacular strike that could threaten the poll itself but carried out intermittent attacks across the country.

Rockets fell on towns, especially in the south and east, and two gunmen wearing suicide vests were killed in a gun battle in Kabul.